Fix style in toxav.c.

[iphydf]

• Use Camel_Snake_Case for type names.
• Use at least 4 characters for constant names. I.e. END is a type
  name, but RETURN is a constant name. This is because DHT is a type
  name (yay consistency).
• Using min_* functions instead of MIN, we can avoid a cast.
• Use for-loops for for-each-frame semantics instead of while.
• Don't use assignments as expressions.
• ++i instead of i++.
• Function pointers are dereferenced automatically, so no need to
  manually do so.
• Avoid void pointers that lie about not being spaghetti code. Toxcore
  and toxav are both spaghetti and shouldn't pretend anything else.
• Don't use empty statements (e.g. no ;; anywhere in the code).

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This change is 

[sudden6]

Reviewable status: 0 of 1 approvals obtained (waiting on @iphydf)

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toxav/toxav.h, line 748 at r1 (raw file):

 */
int toxav_add_av_groupchat(Tox *tox,
                           void (*audio_callback)(void *, uint32_t, uint32_t, const int16_t *, unsigned int, uint8_t, uint32_t, void *),

make audio_callback a type?

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toxav/toxav.c, line 188 at r1 (raw file):

    msi_register_callback(av->msi, callback_capabilites, MSI_ON_CAPABILITIES);

RETURN:

maybe call this one FAIL or EXIT? `return has a very specific meaning in C, so I think we should avoid that.

[iphydf]

Reviewable status: 1 change requests, 0 of 1 approvals obtained (waiting on @iphydf)

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toxav/toxav.h, line 748 at r1 (raw file):

Previously, sudden6 wrote…

make audio_callback a type?

It is a type in groupav.h, but I don't want to expose it in the public api, because it's a non-sensical type. It says tox is a void pointer, when clearly it should be a Tox pointer. We can't fix this right now, so I'll fix it in 0.3.0. I've added a todo above.

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toxav/toxav.c, line 188 at r1 (raw file):

Previously, sudden6 wrote…

maybe call this one FAIL or EXIT? `return has a very specific meaning in C, so I think we should avoid that.

I considered FAIL, but this is all the returns, not just the error returns. "exit" also has a specific meaning, namely to terminate the program. This is in fact jumping to the return statement, and since we're C, not C++, we have to actually spell out all the destructors that would normally be inserted at a real "return" statement.

Thoughts?

[sudden6]

Reviewed 2 of 3 files at r2.
Reviewable status: 1 change requests, 0 of 1 approvals obtained (waiting on @sudden6)

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toxav/toxav.c, line 188 at r1 (raw file):

Previously, iphydf wrote…

I considered FAIL, but this is all the returns, not just the error returns. "exit" also has a specific meaning, namely to terminate the program. This is in fact jumping to the return statement, and since we're C, not C++, we have to actually spell out all the destructors that would normally be inserted at a real "return" statement.

Thoughts?

I have also seen CLEANUP being used for this, it would not clash with any C specific key words AFAIK, that we have to call all destructors ourself is unfortunate, I know...

Feel free to choose your preferred label, there probably isn't a single best solution.

[sudden6]

Reviewed 1 of 3 files at r2.
Reviewable status: 1 change requests, 0 of 1 approvals obtained (waiting on @iphydf)